Shielded knife

ABSTRACT

A knife assembly having a blade disposed adjacent a shield and secured to a handle, with the shield being resiliently mounted with respect to the handle so that cutting pressure retracts the shield to expose the cutting edge of the blade.

United States Patent inventor Harry Suupanski 7S5 Oakleigh, N.W., Grand Rapids, Mich. 49504 Appl. No 739,435 Filed June 24, 1968 Patented July 6, 1971 SHIELDED KNIFE 2 Claims, 22 Drawing Figs.

US. Cl 30/151, 30/295 llnt. Cl B261) 29/02 Field of Search 30/286, 289, 287, 290, 292, 293, 295, 151

References Cited UNITED STATES PATENTS 2,644,230 7/1953 Anderson 30/151 329,019 10/1885 Cole 30/292 623,000 4/1899 Erkenbreck 30/292 920,980 5/1909 Moore 30/292 1,222,366 4/1917 Curry 30/286 1,871,968 3/1932 Ege 30/293 2,743,523 5/1956 Honey 30/286 FOREIGN PATENTS 200,951 7/1923 Great Britain 30/290 Primary Examiner-Robert C. Riordon Assistant Examiner-J. C. Peters Attorney-Glenn B. Morse ABSTRACT: A knife assembly having a blade disposed adjacent a shield and secured to a handle, with the shield being resiliently mounted with respect to the handle so that cutting pressure retracts the shield to expose the cutting edge of the blade.

PATENIED JUL 6 IBYI SHEET 1 BF 3 INVENTOR. HARRY SZCZEPA NSK/ PATENTEUJUL 6I97l 3,590,483

SHEET 3 OF 3 SHIELDED KNIFE BACKGROUND There are a number of uses for a sharp blade, but many of them are impractical if it is necessary to withdraw and sheath a fixed knife, or open and shut a folding knife, to avoid the hazard of leaving an exposed blade around unguarded. In offices and shipping rooms, cutting twine and paper is an opera tion repeated frequently enough to represent quite a time factor. The full value of the knife is only realized if it can be slipped into a pocket or drawer when not in use, and will neither endanger the person handling it, nor destroy its edge by accidental collision with hard objects. Applicant is not aware of any form of a pocket-size shielded knife that projects the blade out of shielded position by the forces involved in using the knife, and thus automatically assures a safe condition of the blade when not in use, and eliminates the operation of preparing the knife for use.

SUMMARY OF THE INVENTION This invention provides for the automatic projection of the cutting edge of the blade beyond a shielding plate (by the normal forces involved in a cutting operation) through incorporating a resilient mounting for the shield which permits dis placement of the shield with respect to the handle with which the cutting forces are applied. A relatively rigid connection between the blade and the handle transmits these forces, which are initially resisted by the resilient mounting of the shielding plate. As these forces are increased, the shielding plate retracts, and slips over the surface of the knife to expose the edge for cutting. The shield thus slides along the material being cut, and serves to stabilize it as the cutting operation proceeds. The resilient mounting of the shield is determined such that the forces required to retract the shielding plate are less than those normally used in the cutting operation. In the preferred form of the invention, a disclike assembly incorporates a housing section on opposite sides of a circular blade, which is sandwiched between a pair of shield plates. These shield plates are positioned by rubber rings concentric with the assembly, with the opening of the rings being traversed by the locating structure of the housing. An alternative form of the invention makes use of standard forms of razor blades, which usually have straight edges. Structure of a housing, or fixed with respect to it, traverses the standard openings in the blade, and the shielding plate or plates is also provided with openings opposite these same areas. Resilient support of the shield plate with respect to the housing structure on pieces of rubberlike material provides for the automatic projection and retractions referred to above. The blade is preferably traversed at least at two spaced points to avoid a tendency to rotate the blade as pressure is applied at a particular part of the assembly.

DESCRIPTION OF THE DRAWINGS The several features of the present invention will be analyzed in detail through a discussion of the particular embodiments illustrated in the accompanying drawings. In the drawings:

FIG. 1 is a side elevation of a circular knife ing the invention.

FIG. 2 is an edge view of the unit shown in FIG. 1.

FIG. 3 is a section through the axis of the unit shown in FIG. 1.

FIG. 4 is a side view of the knife assembly shown in FIGS. 1 to 3, showing the projection of the cutting blade under operat ing pressure.

FIG. 5 is an edge view of the knife under the condition shown in FIG. 4.

FIG. 6 is a sectional elevation of a modified form of the invention.

FIG. 7 shows a further modification of the invention, to incorporate a twine-severing feature.

assembly involv- FIG. 8 is a section on the plane 8-8 of FIG. 7.

FIG. 9 is a side elevation showing a further modification of the invention.

FIG. 10 is a section on the plane 10-10 of FIG. 9.

FIG. 11 is a side elevation showing the FIG. 9 modification in use.

FIG. 12 is a side elevation of a further modification of the invention.

FIG..13 is a section through the axis of the FIG. 12 modification.

FIG. 14 is a side elevation of a modification of the invention utilizing parallel-edge razor blades.

FIG. 15 is an end view of the modification shown in FIG. 14.

FIG. 16 is a section on an enlarged scale on the plane 16-16 of FIG. 14.

FIG. 17 is a section on an enlarged scale on the plane 17-17 of FIG. 14.

FIG. 18 is a view of a further modification of the invention, adapted to utilize standard razor blades having a single straight edge.

FIG. 19 is a section on the plane 19-19 of FIG. 18, with the housing components removed.

FIG. 20 is a section on the plane 20-20 of FIG. 18.

FIG. 21 is a section on the plane 21-21 of FIG. 18.

FIG. 22 is a side elevation of the blade and shield assembly utilized in the FIG. 18 modification, with the handle-housing removed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 through 5, the illustrated knife assembly includes the opposite handle-housing sections 30 and 31, the blade 32, the shield plates 33 and 34, the rubber 0- rings 35 and 36, and the securing screw 37. The handle-housing sections are provided with the central bosses 38 and 39, respectively, and the boss 38 is threaded to receive the screw 37. The crew passes through the boss 39 of the handle-housing section 31 with clearance. The shield 33 has a central annular flange 40, and the shield 34 has a similar flange 41. The 0- rings are interposed between the shield flanges and the central bosses to provide a resilient mounting for the shields that will permit radial forces to induce retraction of the shields with respect to the handle-housing sections, and thus extend the blade 32 on one side to project the cutting edge 42 beyond the periphery of the shields. This action is generated by the application of cutting pressure to the handle-housing units, and the shielded position shown in FIG. 3 is immediately restored after the pressure has been removed. The shape of the device makes it possible to hold it between the thumb and forefinger, and slice along a line in about the same manner as if the blade alone were used. The blade moves with the handle-housing sections, as a result of the relatively close fit between the screw 37 and the central opening in the blade 32 traversed by this screw. The action of the device is best shown in FIG. 4, and it will be noted that the blade has now assumed a position eccentric with respect to the shields, and it is now cutting the sheet 43. The illustrated configuration of the handle-housing sections 30 and 31 facilitates the use of the device between the fingers by the presence of the recesses 44 and 45.

The modification illustrated in FIG. 6 is essentially similar to that of FIG. 3, but utilizing a square cross-sectional configuration for the resilient rings 46 and 47, rather than the circular cross section shown in FIG. 3. Since the distortion of the resilient rings will usually generate a lateral expansion, if the material of the rings is solid, the O-configuration provides a lateral space for the distortion of the ring material. With a ring of a rectangular cross section that fully occupies the space in its original condition, as shown in FIG. 6, the rings 46 and 47 should be of a foamed material which does not require flow space. The handle-housing sections 48 and 49 are functionally similar to the sections 30 and 31 of FIG. 3, and the shields 50 and 51 and the blade 52 can be identical with the FIG. 3 modification. The central screw 37 of FIG. 3 has been placed by an adhesively secured dowel 53 in FIG. 6, and this construction may be considered as appropriate for a high-volume jacent this fold forms a, hook 57 and a slot 58 exposing the blade 59, so that a length of twine can be snagged under the hook 57 and subject to the edge of the blade 59 without sacrificing the shielded characteristic of the blade, or requiring extensive blade pressure to expose the blade beyond the shields. The remainder of the periphery of the device functions in the same way as that described in connection with the FIG. 3 and FIG. 6 modifications. The structure in the central area of the FIGS. 7 and 8 modification may be considered as similar to that shown in FIG. 3.

FIGS. 9 and 10 show a further modification of the device, in which the shield and housing are formed as an integral unit. The housing may be considered as the central parts 60 and 61 of the opposite sections 62 and 63, which are formed of resilient material. TI-Ie flexible rims 64 and 65 form the shielding members, and these are connected to the central handle portions 60 and 61 by spoke sections 66-71. The sections 62 and 63 are held in engagement with the blade 72 by the post 73 and the screw 74. The post is in closely fitting engagement the central hole of the blade 72, so that forces can be transmitted directly to the blade to induce deflection of the rims 64 and 65 for blade exposure, as shown in FIG. .11. FIGS. 12 and 13 illustrate a similar type of operation, but utilizing relatively thin-wall materials that are deflectable through a different pattern of bending than that characteristic of the cross section shown in FIG. 10. The handle cups 75 and 76 are of relatively stiff material, and the shield sections 77 and 78 are sufficiently deflectable by application of pressure to expose the cutting edge 79 of the blade 80. A central rivet assembly 81 secures the assembly together. The blade 80 has a relatively close fit around the rivet assembly 81, which transmits pressure directly to the blade.

FIGS. 14 through 17 illustrate a knife assembly utilizing a standard double-edged razor blade. The blade 82 has its standard central aperture 83 traversed by a screw 84 engaging a nut 85 holding the handle-housing sections 86 and 87 together. Pins 88 and 89 are secured to the housing section 87, as by deforming the ends in the manner of a rivet, as shown at 90 in FIG. 16. The pins traverse the central opening 83 in the blade at spaced points, and each of these serves to locate a pair of O-rings 91 and 92 disposed on opposite sides of the blade 82. The shield plates 93 and 94 are each provided with central annular flanges 95 and 96, respectively, engaging the outer portions of the "Orings. This arrangement produces a resilient mounting of the shield plates with respect to the handle-housing sections, and consequently with respect to the blade 82 as well. The cuttingedges 97 and 98 can thus be projected beyond the adjacent edges 99-100 and 101-102 of the shield plates whenever sufficient pressure is applied through the handle-housing sections to cause the forces at the plate edges to deform the O-rings and slip the shield plates back from the adjacent cutting edges. Both the shields and the blade have clearance over the screw 84. Under the usual type of use, one corner or another of the unit illustrated in FIG. 14 will receive the cutting pressure, and the shields will be retracted in that area. The effect is a slight pivoting action of the shield about the opposite of the pins 88 or 89.

FIGS. 18 through 21 illustrates a form of the invention that is usable with a conventional single-edge razor blade. The usual narrowness of these blades makes it desirable to use an adapter 103 as a means of securing the blade 104 with respect to the handle-housing sections 105 and 106. The adapter 103 is lanced out as shown at 107 and 108 in FIG. 19 to provide projections entering into the standard apertures 109 and 110 in the blades 104. The adapter and blade are secured with respect to the handle-housin g sections by the engagement of a central opening in the adapter 103 with the periphery of the nut 111 engaged by the screw 1 12. This arrangement is shown in FIG. 21, and the resilient mounting of the shield plate 113 with respect to the assembly is shown in FIG. 20. The pins 114 and 115 may be considered as fixed with respect to either the housing section 105 or the section 106, and are immediately surrounded by deformable resilient rings as shown at 116 in FIG. 20. The shield plate 113 has a flange 117 bearing against one side of the deformable rings, so that pressure at one comer or the other of. the device can rock the shielded plate 113 about its central opening engaging the nut 111, indicated in FIG. 21. It is not particularly necessary to completely surround the resilient ring 116 by portions of the shield plate, as pressure at either of the opposite sides will induce the retracting and return movement.

The particular embodiments of the present invention which have been illustrated and discussed herein are for illustrative purposes only, and are not to be considered as a limitation upon the scope of the appended claims. In these claims, it is my intent to claim the entire invention disclosed herein, except as I am limited by the prior art.

I claim:

1. A knife having a blade and a shield, wherein the improvement comprises:

at least one housing member provided with a manual gripping surface, and including a pair of components on opposite sides of said blade secured together by central tie means;

a blade normally relatively fixed with respect to said housing member; and at least one shield member disposed adjacent said blade and disposed within said housing except for a peripheral edge portion projecting from said housing, and resiliently mounted with respect to said housing member, said shield member normally extending to a pressure edge disposed beyond and adjacent the cutting edge of said blade, said shield member being retractable under pressure applied at said pressure edge to a position exposing said cutting edge, said housing, blade, and shield member being annular, said knife also including a resilient central ring disposed within a central opening in said shield member, said resilient ring being traversed by structure fixed with respect to said housing.

2. A knife having a blade and a shield, wherein the improvement comprises:

at least one housing member provided with a manual gripping surface;

a blade normally relatively fixed with respect to said housing member; and

at least one shield member disposed adjacent said blade and disposed within said housing except for a peripheral edge portion projecting from said housing, and resiliently mounted with respect to said housing member, said shield member normally extending to a pressure edge disposed beyond and adjacent the cutting edge of said blade, said shield member being retractable under pressure applied at said pressure edge to a position exposing said cutting edge, said shield member having openings traversed by structure fixed with respect to said housing, said knife additionally including a resilient ring interposed between said structure and said shield member in said opening. 

1. A knife having a blade and a shield, wherein the improvement comprises: at least one housing member provided with a manual gripping surface, and including a pair of components on opposite sides of said blade secured together by central tie means; a blade normally relatively fixed with respect to said housing member; and at least one shield member disposed adjacent said blade and disposed within said housing except for a peripheral edge portion projecting from said housing, and resiliently mounted with respect to said housing member, said shield member normally extending to a pressure edge disposed beyond and adjacent the cutting edge of said blade, said shield member being retractable under pressure applied at said pressure edge to a position exposing said cutting edge, said housing, blade, and shield member being annular, said knife also including a resilient central ring disposed within a central opening in said shield member, said resilient ring being traversed by structure fixed with respect to said housing.
 2. A knife having a blade and a shield, wherein the improvement comprises: at least one housing member provided with a manual gripping surface; a blade normally relatively fixed with respect to said housing member; and at least one shield member disposed adjacent said blade and disposed within said housing except for a peripheral edge portion projecting from said housing, and resiliently mounted with respect to said housing member, said shield member normally extending to a pressure edge disposed beyond and adjacent the cutting edge of said blade, said shield member being retractable under pressure applied at said pressure edge to a position exposing said cutting edge, said shield member having openings traversed by structure fixed with respect to said housing, said knife additionally including a resilient ring inTerposed between said structure and said shield member in said opening. 